code: def close(self):
      self.db.close()
  
file_path: BigDL/python/serving/src/bigdl/serving/kafka/client.py
imports: from kafka import KafkaProducer, KafkaConsumer
  from kafka.errors import kafka_errors
  import json
  from bigdl.serving.schema import *
  from bigdl.serving.log4Error import invalidInputError
label_desc: Use image node_id 5 for calling the OutputQueue obj's underlying member method code with example usage: obj.close() without return types